Henri Gomez said: > Henri Gomez a écrit : >>> Nope since you don't have to just test at protocol level but also on >>> higher level, for instance check the full chain, up to servlet >>> handling. >>> >>>> It's easy to simulate this behavior by sending a STOP signal to >>>> Tomcat. >>>> >>>> I've also attached a log from mod_jk showing the problem. I marked >>>> the >>>> point at which processing in mod_jk stopped until I sent a CONT >>>> signal to >>>> tomcat. >>>> >>>> Does mod_jk2 have this same problem? Is there any interest in fixing >>>> this? Does anyone have a workaround for this issue? >>> >>> Well, if you have a hung tomcat, you're probably allready in serious >>> trouble.
No, actually in my case I wasn't. I had two Tomcats running, as one was prone to locking up due to a JVM or application bug. With a 50-50 load distribution between two Tomcats, this left me with 1/2 of the requests getting stuck and clients waiting forever and tying up Apache processes. Eventually, a DOS will be the result if action is not taken in time. If mod_jk noticed it wasn't really alive, this wouldn't be an issue at all. >>> Anyway, if we add stuff like time-out in ajp request, you could be >>> stuck with long running servlets. Also jk read request in a blocking >>> mode for performance and adding timeout here is not an option. Agreed that we wouldn't want a timeout normally to handle normal long running servlet processes, but if there was a PING/PONG added to the protocol there should be a timeout to prevent the above situation. >> When I worked on ajp13++ (ajp14) protocol, I added a more secure auth >> mecanism at connection time. >> >> Since there is a bidirectionnal communication, jk could detect that >> even if the connection is open, the remote didn't respond and so fall >> back to the next in cluster configuration. >> >> But on allready established connections, the problem persist. >> >> Or we should add a PING/PONG before sending any request to tomcat. >> >> It could be done as optional but I work on it only if many users make >> such requirements > > if many users ask for such feature ;) Well, you've got one so far. ;-) Adding a configurable option to have mod_jk verify (PING/PONG) that Tomcat is actually responding before using the connection would solve the problem and I can't imagine that it would add a lot of complexity to the code as well. If I wasn't so rusty with my C programming and had some spare time, I would offer to help code it up. ;-) In any case, I'll be more than happy to help test. Thanks, Dave -Dave --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
